1. Field of the Invention
The present invention relates to a vehicle body structure. More particularly, it relates to the body structure in the circumference of an air box of the vehicle body.
2. Description of Related Art
As the earlier art body structure in the circumference of the air box in a vehicle, Japanese Patent Publication (kokai) No. 6-329051 discloses one body structure where the air box is connected with both of a front pillar and a hood ridge on one side of the vehicle body.
In detail, the air box is arranged so as to extend along the direction of a vehicle's width, forming an automotive framework member. The above front pillar is arranged on each end of the air box in the vehicle's width direction. Each front pillar is arranged to extend along the upward-and-downward direction of the vehicle body, also forming one automotive framework member. The hood ridge is arranged on each side of the vehicle body, in its front section. On each side of the vehicle body, the hood ridge is arranged to extend along the fore-and-aft direction of the vehicle body, also forming one automotive framework member.
The air box is provided, on each side in the width direction, with a horizontal flange. On the other hand, the hood ridge has a joint surface defined for integration with the air box. In assembling, the above horizontal flange of the air box is piled on the joint surface defined on the hood ridge. Successively, the flange is connected to the joint surface by welding. Besides the joint surface, the hood ridge has a lateral flange formed to project from its sidewall sideways. While, the front pillar has a flange formed to project from its sidewall sideways, for abutment with the lateral flange of the hood ridge. In order to connect the front pillar with the hood ridge on each side of the vehicle body, the lateral flange of the hood ridge is butted against the flange of the front pillar and successively welded to the same flange into one body.
However, the above-mentioned body structure has a problem to be solved.
That is, if an external force via an automotive suspension in the upward-and-downward direction, so-called "suspension input" is applied on the hood ridge, the resultant bending of the hood ridge allows a force to act on the above connections between the air box and the hood ridge and between the hood ridge and the front pillar in a direction to separate the horizontal flange of the air box from the joint surface of the hood ridge and separate the lateral flange of the hood ridge from the flange of the front pillar. In order to avoid the occurrence of separations, it is necessary to enhance the bending rigidity of the hood ridge, for example, by increasing a plate thickness of each constituent of the structure. However, such an increase in plate thickness causes the body structure to be heavy-weighted as a matter of course.
Meanwhile, in view of reducing the weight of a vehicle body and the number of its components, there is a vehicle body on recent development, which is made of a casting of light metal, for example, aluminum alloy, manganese alloy, etc.
In spite of the attempt for lightweight, the above-mentioned conventional body structure still causes the plate thickness to be increased in view of ensuring the bending rigidity of each hood ridge. In other words, there is still remained a limit for the light-weighted body structure due to such an increase in plate thickness.